JP2005145102A - Floor panel structure for automobile and method of manufacturing the floor panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a floor panel structure of an automobile capable of reducing noise in a vehicle cabin. <P>SOLUTION: In this floor panel of a vehicle body having vibration mode adjusting structure for suppressing the occurrence of the acoustic radiation of floor panels by generating the vibration of a specified mode, the floor of the automobile is formed of floor panels S1, S2, S5, and S6 connected to the frame members 12, 14, 16, 18, 20, 22, 24, and 26 of the vehicle body. The vibration mode adjusting structure of the floor panels comprises a rigid adjusting part 62 formed by forming the floor panels in a rectangular shape projected upward or downward so that the vibration of 2 x 1 mode or 2 x 2 mode with a frequency approximately equal to the cavity resonance frequency of a tire can be generated on the floor panels. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a vehicle body floor panel structure, and more particularly to a vehicle body floor panel structure in which a floor of an automobile is constituted by a floor panel connected to a vehicle body frame member.

Vibration from the frame member to which the engine and suspension are connected is transmitted to the floor panel, and this floor panel vibrates. As a result, unpleasant vehicle interior vibration and noise are generated by greatly vibrating the air in the vehicle interior. It is known.
In this case, vibrations of the engine itself and road noise transmitted from the suspension become a problem as a vibration source. This road noise is generally caused by tire cavity resonance and suspension resonance caused by tire cavity resonance. There is.

  Conventionally, in order to suppress these vibration noises, damping materials and vibration-proofing materials are generally pasted as various vibration-proofing and sound-proofing measures on each part of the floor panel and the vehicle body in the vicinity thereof. . As a result, vibration and noise can be reduced, but on the other hand, a large amount of vibration damping materials and vibration damping materials are required, which increases the weight of the vehicle, thereby causing various adverse effects and costs. There was a problem.

  Furthermore, in automobiles, unpleasant vibrations transmitted from the engine and suspension are mainly 400 Hz or less, and particularly have a peak at a frequency around 250 Hz, which is road noise caused by tire cavity resonance. It is also known that the rigidity of the panel panel is increased by forming a large number of beads or increasing the panel thickness, thereby shifting the natural frequency of the floor panel to a high band higher than 400 Hz. In this way, unpleasant vibration noise is reduced by preventing the floor panel from resonating in the cavity resonance frequency band of the tire or the resonance frequency band of the suspension.

  In this case, there is an advantage that the resonance peak in the low frequency region can be suppressed, but on the other hand, the vibration in the high frequency region increases on the contrary. As in the case described above, the vehicle weight increases, which causes various adverse effects and problems in terms of cost, and it has been desired to solve these problems.

  Therefore, the present applicant pays attention to the relationship between the vibration frequency of the vibration transmitted to the floor panel and the vibration mode, and proposes a floor panel structure in which the vibration mode has a smaller acoustic radiation level at a specific vibration frequency (resonance region). (Patent Document 1). In this floor panel structure, the vibration mode of the floor panel is 2 × 2 mode in a frequency band near 250 Hz, which is road noise caused by the cavity resonance of the tire transmitted to the floor panel as the most unpleasant vibration as a specific frequency. Or, the rigidity of the floor panel is partially adjusted so that it becomes a vibration mode that generates an even number of vibration antinodes as in the 2 × 1 mode, and the sound waves emitted from each antinode are set to cancel each other out. By doing so, the acoustic radiation efficiency is lowered, and the noise in the passenger compartment is reduced.

JP-A-9-202269

  However, in the floor panel structure in which the vibration damping material and the vibration damping material are pasted on the entire surface of the above-described conventional floor panel, since the vibration damping material and the like are frequently used, the material cost is increased and the weight of the vehicle body is further increased. Problems arise. In addition, when the panel thickness is increased, the vehicle weight increases.

  In addition, the floor panel structure described in Patent Document 1 is useful for reducing noise in a specific frequency band, for example, a frequency band near 250 Hz that is road noise caused by tire cavity resonance. When a 1 × 1 mode with high acoustic radiation efficiency and only one anti-vibration occurs in a frequency band other than the frequency band near 250 Hz, particularly in the frequency band near 160 Hz, it is caused by tire cavity resonance. Even if the noise in the frequency band near 250 Hz, which is the road noise, can be reduced, the problem arises that the noise in the frequency band near 160 Hz, which is the road noise due to the resonance of the suspension, becomes very large.

  Here, in the floor panel structure described in Patent Document 1 described above, a circular rigidity adjusting portion is provided on the floor panel in accordance with the vibration amplitude distribution of vibration mode, more specifically, the strain energy distribution. A vibration mode with low acoustic radiation efficiency such as the 2 × 1 mode is generated.

  Since such a circular rigidity adjusting portion is relatively easy to press and adjusts its size and depth to adjust its rigidity, it is like the 2 × 1 mode. It is necessary to adjust such that a vibration mode with a low acoustic radiation efficiency is generated in a frequency band near 250 Hz and a vibration of a 1 × 1 mode with a high acoustic radiation efficiency is not generated in a frequency band near 160 Hz.

  However, since exhaust pipes, seats, etc. are arranged below and above the vehicle body of the floor panel, it is necessary to control the height so that the rigidity adjustment does not interfere with them, and the foot comfort of the occupant is reduced. In order to secure it, it is necessary to keep it at a certain height. Moreover, it is necessary to make it the size and height which can be pressed. Further, it is necessary to make the rigidity adjusting portion fit within the floor panel having a certain shape and size surrounded by the frame member. That is, in order to adjust the rigidity of the rigidity adjusting portion due to such restrictions on the vehicle body structure or processing, the size and height of the circular rigidity adjusting portion must be adjusted within a predetermined range.

  Therefore, in the adjustment within the predetermined range, it is impossible to prevent the vibration of 1 × 1 mode in the frequency band near 160 Hz, and the noise in the frequency band near 160 Hz becomes very large. In order to simultaneously reduce the vibration in the frequency band of road noise due to the resonance of the suspension, it is necessary to apply a damping material to the entire surface of the floor panel, which increases the weight of the vehicle body. Problems arise.

  In addition, when generating a vibration mode with low acoustic radiation efficiency such as 2 × 1 mode in a specific frequency range by the floor panel structure described in Patent Document 1, if the vibration amplitude itself can be reduced, The noise in the passenger compartment can be further reduced.

  Here, the present inventors have found that when the rigidity of the floor panel is partially increased, the difference in the shape of the portion affects the generation frequency of the vibration mode and the magnitude of the vibration amplitude. Attention was focused on solving the above-mentioned problems of the prior art.

  The present invention has been made to solve the above-described problems of the prior art, and generates a vibration mode with low acoustic radiation efficiency in a specific frequency band (for example, around 250 Hz) and reduces the vibration amplitude. Thus, it is an object of the present invention to provide a floor panel structure for a vehicle body that can greatly reduce noise emitted from the floor panel due to vibration transmitted from the frame member of the vehicle body to the floor panel, thereby reducing noise in the vehicle interior. .

  The present invention generates a vibration mode having a low acoustic radiation efficiency in a specific frequency band (for example, around 250 Hz) and a vibration mode having a high acoustic radiation efficiency in a specific frequency band (for example, near 160 Hz) other than that frequency band. An object of the present invention is to provide a vehicle body floor panel structure capable of greatly reducing the noise emitted from the floor panel due to vibrations transmitted from the frame member of the vehicle body to the floor panel so that the noise in the vehicle interior can be reduced. It is said.

  In order to achieve the above object, the present invention provides a vibration that suppresses generation of acoustic radiation of a floor panel by forming a floor of an automobile with a floor panel connected to a frame member of a vehicle body and generating vibration in a predetermined mode. A floor panel structure of a vehicle body having a mode adjustment structure, wherein the vibration mode adjustment structure of the floor panel applies a vibration of 2 × 1 mode or 2 × 2 mode to the floor panel in a frequency band substantially matching a tire cavity resonance frequency. It is characterized by having a rigidity adjusting portion formed in a rectangular shape with the floor panel protruding upward or downward so as to be generated.

In the present invention configured as described above, the vibration mode adjusting structure of the floor panel generates 2 × 1 mode or 2 × 2 mode vibrations in the floor panel in a frequency band that substantially matches the cavity resonance frequency of the tire. In addition, since it has a rigidity adjusting portion formed in a rectangular shape in which the floor panel protrudes upward or downward, vibration of 2 × 1 mode or 2 × 2 mode is generated in a frequency band that substantially matches the cavity resonance frequency of the tire. Thus, it is possible to greatly reduce noise emitted from the floor panel due to vibration transmitted from the frame member of the vehicle body to the floor panel, thereby reducing noise in the vehicle interior.
In addition, since the rigidity adjusting portion is rectangular, the vibration amplitude of the antinode of 2 × 1 mode or 2 × 2 mode can be reduced, and as a result, in addition to the canceling effect of canceling each other, Furthermore, the radiated sound itself can be further reduced.
In addition, since the rigidity adjusting portion has a rectangular shape, it is easy to define a region where vibration antinodes occur in the vibration region of the floor panel, and as a result, the vibration volumes of adjacent antinodes of vibrations are made the same. The acoustic radiation efficiency can be greatly reduced.
In addition, since the rigidity adjusting portion is rectangular, the outer peripheral edge thereof is formed in a straight line, making it less likely to generate 1 × 1 mode vibration than forming the rigidity adjusting portion in a circular shape, or Even when the 1 × 1 vibration mode is generated, the generated frequency can be increased to be closer to the generated frequency of the 2 × 1 or 2 × 2 mode.

  The present invention also provides a vehicle body having a vibration mode adjustment structure that constitutes a floor of an automobile by a floor panel connected to a frame member of the vehicle body and that suppresses generation of acoustic radiation of the floor panel by generating vibration in a predetermined mode. The floor panel vibration mode adjustment structure is configured to move the floor panel upward or downward so as to generate 2 × 1 mode or 2 × 2 mode vibration in a frequency band near 250 Hz. It has a rigidity adjusting portion formed in a protruding rectangular shape.

In the present invention configured as described above, the floor panel vibration mode adjustment structure raises the floor panel so that the floor panel generates vibration of 2 × 1 mode or 2 × 2 mode in a frequency band near 250 Hz. Or, it has a rigid adjustment part formed in a rectangular shape that protrudes downward, so that vibration in the 2 × 1 mode or 2 × 2 mode is generated in the frequency band near 250 Hz, and the vibration transmitted from the frame member of the vehicle body to the floor panel The noise emitted from the floor panel can be greatly reduced to reduce the noise in the passenger compartment.
In addition, since the rigidity adjusting portion is rectangular, the vibration amplitude of the antinode of 2 × 1 mode or 2 × 2 mode can be reduced, and as a result, in addition to the canceling effect of canceling each other, Furthermore, the radiated sound itself can be further reduced.
In addition, since the rigidity adjusting portion has a rectangular shape, it is easy to define a region where vibration antinodes occur in the vibration region of the floor panel, and as a result, the vibration volumes of adjacent antinodes of vibrations are made the same. The acoustic radiation efficiency can be greatly reduced.

  Furthermore, the present invention provides a vehicle body having a vibration mode adjustment structure that forms a floor of an automobile with a floor panel connected to a frame member of the vehicle body and suppresses generation of acoustic radiation of the floor panel by generating vibration in a predetermined mode. The floor panel vibration mode adjustment structure is configured to move the floor panel upward or downward so as to generate 2 × 1 mode or 2 × 2 mode vibration in a frequency band near 250 Hz. If there is a protruding stiffness adjustment part and a 1 × 1 vibration mode can be generated in a frequency band other than around 160 Hz, the rigidity adjustment part is formed in a circular shape and the 1 × 1 vibration mode is When it cannot be generated in a frequency band other than around 160 Hz, the rigidity adjusting portion is formed in a rectangular shape.

In the present invention configured as described above, the vibration mode adjustment structure of the floor panel moves the floor panel upward so that vibration of 2 × 1 mode or 2 × 2 mode is generated in the floor panel in a frequency band near 250 Hz. Alternatively, in the case of having a rigidity adjusting portion protruding downward and generating a 1 × 1 vibration mode in a frequency band other than near 160 Hz, the rigidity adjusting portion is formed in a circular shape, and 1 × 1 When the vibration mode cannot be generated in a frequency band other than around 160 Hz, the rigidity adjusting portion is formed in a rectangular shape, so that the 2 × 1 mode or the 2 × 2 mode is set to a frequency band around 250 Hz, for example, , The sound emitted from the floor panel due to road noise due to cavity resonance of tires in the frequency band of 220 to 260 Hz can be reduced, and the frequency of 1 × 1 mode is around 160 Hz. , For example, it can be reduced radiated sound due to road noise due to suspension resonance of the frequency band of 120 to 180 Hz.
In addition, when the 1 × 1 vibration mode can be generated in a frequency band other than around 160 Hz, the rigidity adjusting portion is formed in a circular shape. Here, the circular rigidity adjusting portion is relatively easy to press, and can be made difficult to generate bending vibration or torsional vibration in the rigidity adjusting portion itself by being inflated into a dome shape. Therefore, it is possible to reduce the cost of press working and to reduce the radiated sound due to road noise due to the resonance of the suspension in the frequency band near 160 Hz, for example, the frequency band of 120 to 180 Hz.
In addition, when the 1 × 1 vibration mode cannot be generated in a frequency band other than around 160 Hz, the rigidity adjusting portion is formed in a rectangular shape. Here, when the rigidity adjusting portion is formed in a rectangular shape, the outer peripheral edge portion is formed in a straight line shape, so that vibration of 1 × 1 mode is generated rather than forming the rigidity adjusting portion in a circular shape. When the 1 × 1 vibration mode is generated, the generated frequency can be increased to be closer to the generated frequency of the 2 × 1 or 2 × 2 mode. It is possible to prevent the mode from occurring in a frequency band near 160 Hz. Therefore, it is possible to reduce radiated sound due to road noise due to resonance of a suspension in a frequency band near 160 Hz, for example, a frequency band of 120 to 180 Hz.

  In the present invention, preferably, the vibration mode adjustment structure includes two rectangular rigidity adjusting portions, each side of each of the rigidity adjusting portions is opposed and parallel to each other, and is elongated between the rigidity adjusting portions. Arranged to form a panel portion and generate a 2 × 1 vibration mode.

  In the present invention configured as described above, the vibration mode adjustment structure includes two rectangular rigidity adjustment parts, and each rigidity adjustment part is opposed to and parallel to each other. Are arranged so as to form an elongated panel portion between them, and a 2 × 1 vibration mode is generated, so that the vibration panel is surely generated in the elongated panel portion to define the position of the vibration node and 2 * 1 mode vibration can be generated reliably. Further, it is difficult to generate the vibration of the 1 × 1 mode itself, or even if it occurs, the vibration amplitude can be reduced.

  In the present invention, it is preferable that the vibration mode adjustment structure has four rectangular rigidity adjustment portions, each side of the rigidity adjustment portions adjacent to each other is opposed to and parallel to each other, and the four rigidity adjustment portions are used. It is arranged so as to form an elongated panel portion extending in a cross shape, and generates 2 × 2 mode vibration.

  In the present invention configured as described above, the vibration mode adjustment structure has four rectangular rigidity adjustment parts, and each of the adjacent rigidity adjustment parts faces each other and is parallel to each other. It is arranged so as to form an elongated panel portion extending in a cross shape by the rigidity adjusting portion, and 2 × 2 mode vibration is generated, so that a vibration vibration node is surely generated in the elongated panel portion, and the position of the vibration node is determined. And 2 × 2 mode vibration can be reliably generated. Further, it is difficult to generate the vibration of the 1 × 1 mode itself, or even if it occurs, the vibration amplitude can be reduced.

  In the present invention, preferably, the rectangular rigidity adjusting portion of the vibration mode adjusting structure has a step portion provided at an outer peripheral edge portion thereof, and a protruding portion provided inside the step portion, Each of the stepped portion and the protruding portion includes a rising portion, and the rising portion of the stepped portion is formed at an angle closer to the vertical than the rising portion of the protruding portion.

The present invention configured as described above has a stepped portion provided at the outer peripheral edge portion thereof and a protruding portion provided inward of the stepped portion, and the stepped portion and the protruding portion each rise. A step-shaped rising portion is formed at an angle closer to the vertical than the protruding portion rising portion, so that the stepped portion is not provided, for example, a rectangular-shaped rigidity composed only of the protruding portion. The 1 × 1 mode vibration frequency is less likely to be generated than the adjustment unit, or even if the 1 × 1 vibration mode is generated, the 1 × 1 mode generation frequency is set to the 2 × 1 or 2 × 2 mode generation frequency. Can be even closer. As a result, depending on the size and arrangement of the rectangular rigidity adjusting portion, it becomes easy to prevent a 1 × 1 vibration mode from being generated in a frequency band near 160 Hz, and near 160 Hz, which is road noise due to suspension resonance. It becomes easy to reduce the radiated sound from the floor panel due to the frequency.
Further, the rectangular rigidity adjusting portion of the vibration mode adjusting structure has a step portion provided on the outer peripheral edge portion thereof and a protruding portion provided inward of the step portion. Since each part has a rising part and the rising part of the stepped part is formed at an angle closer to the vertical than the rising part of the protruding part, the rigidity of the entire rectangular rigidity adjusting part can be easily increased. . Here, since the outer periphery of the rectangular-shaped rigidity adjusting portion is formed by a straight side, bending vibration and torsional vibration are likely to occur in the rigidity adjusting portion itself as compared to the circular rigidity adjusting portion. However, by increasing the rigidity in this way, it is possible to suppress the occurrence of bending vibration and torsional vibration of the rigidity adjusting unit itself.
Further, the rectangular rigidity adjusting portion of the vibration mode adjusting structure has a step portion provided on the outer peripheral edge portion thereof and a protruding portion provided inward of the step portion. Since each part has a rising part, and the rising part of the step part is formed at an angle closer to the vertical than the rising part of the protruding part, the molding accuracy of the rigidity adjusting part can be increased during press molding, As a result, 2 × 2 and 2 × 1 vibration modes can be reliably generated in a frequency band near 250 Hz.

  The present invention has a vibration mode adjustment structure that is connected to a frame member of a vehicle body and that constitutes a floor of an automobile and that suppresses the generation of acoustic radiation by generating vibrations of a predetermined mode. And / or a method of manufacturing a floor panel of a vehicle body having a rectangular rigidity adjusting portion, wherein the vibration of 2 × 1 mode or 2 × 2 mode is adjusted by adjusting the dimension of the rigidity adjusting portion within a predetermined range. A step of forming a circular rigidity adjusting portion, and a step of forming a circular rigidity adjusting portion when the 1 × 1 mode vibration can be generated in a frequency band other than near 160 Hz. If the 1 × 1 mode vibration cannot be generated in a frequency band other than around 160 Hz even when the dimensions of the rectangular shape are adjusted within a predetermined range, the step of forming the rectangular rigidity adjusting portion is performed. And having a flop, a.

  In the present invention, preferably, in the step of forming the rectangular rigidity adjusting portion, the 1 × 1 mode vibration is not generated or the 1 × 1 mode vibration is not generated by adjusting the dimension of the rigidity adjusting portion within a predetermined range. Can be generated in a frequency band other than the vicinity of 160 Hz, the first step of forming a rectangular rigidity adjusting portion having no step portion on the outer peripheral edge thereof, and the dimensions of the rectangular rigidity adjusting portion If the 1 × 1 mode vibration does not occur even if the frequency is adjusted within a predetermined range, or the 1 × 1 mode vibration cannot be generated in a frequency band other than around 160 Hz, a stepped portion is formed on the outer peripheral edge. A second step of forming a rectangular rigidity adjusting portion having

In this invention comprised in this way, it has the 1st step which forms the rectangular-shaped rigidity adjustment part which does not have a level | step-difference part in the outer periphery part. Here, the rectangular rigidity adjusting portion having no step portion on the outer peripheral edge portion does not need to press the step portion, can reduce the processing cost, and further has a rectangular shape provided with the step portion. Since it is relatively easy to form the rigidity adjusting portion so that the rigidity is lower than the rigidity adjusting portion of, for example, when 1 × 1 mode vibration is generated at a frequency lower than the frequency band near 160 Hz Even when it is not desired to increase the rigidity so much, it is possible to prevent the 1 × 1 mode vibration from being generated in the frequency band near 160 Hz.
Moreover, since it has the 2nd step which forms the rectangular-shaped rigidity adjustment part which has a level | step-difference part in the outer periphery part, compared with the rectangular-shaped rigidity adjustment part which does not provide a level | step-difference part, it is 1x1 mode. It is possible to make vibration less likely to occur, or even if a 1 × 1 vibration mode occurs, the generated frequency of 1 × 1 mode can be made closer to the generated frequency of 2 × 1 or 2 × 2 mode, and as a result, The 1 × 1 vibration mode can be prevented from being generated in a frequency band near 160 Hz.

  ADVANTAGE OF THE INVENTION According to this invention, the radiation sound of a floor panel by the vibration transmitted to the floor panel from the frame member of a vehicle body can be reduced significantly.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a plan view showing an underbody of an automobile having a vehicle floor panel structure according to an embodiment of the present invention.
As shown in FIG. 1, an underbody 1 of an automobile includes a plurality of frame members described later, a front floor panel 2 constituting a floor portion (floor portion) of a passenger compartment connected to these frame members, A center floor panel 4 disposed at a position one step higher than the center of the floor panel 2, and a rear floor panel disposed at a position one step higher than the center floor panel 4 and constituting a floor portion of the luggage compartment 6.
The frame members include a front side frame 10, a side sill 12, a floor side frame 14, a rear side frame 16, 1 cross member 18, no. 2 cross member 20, sub cross member 22, No. 2 3 cross member 24 and No. 3 4 cross member 26.

Next, the frame member will be specifically described with reference to FIG. Side sills 12 having a closed cross-sectional structure extend in the longitudinal direction of the vehicle body as reinforcing members in the longitudinal direction of the vehicle body at both ends in the vehicle width direction of the underbody 1 of the automobile, and the front portions of these side sills 12 are reinforcing members in the lateral direction of the vehicle. No. One cross member 18 is joined. Further, a pair of floor side frames 14 having a closed cross-sectional structure are provided between the side sills 12 so as to extend in the longitudinal direction of the vehicle body.
The front ends of these floor side frames 14 are joined to a pair of front side frames 10 provided so as to surround the left and right sides of the engine room. An engine 28 and a front suspension cross member 30 are attached to the front side frame 10, and a front suspension 32 is attached to the front suspension cross member 30.
A rear side frame 16 having a closed cross-sectional structure extending in the longitudinal direction of the vehicle body is joined to the inner side in the vehicle width direction of the rear portion of each side sill 12, and a rear suspension cross member 34 is attached to the rear side frame 16. A rear suspension 36 is attached to the rear suspension cross member 34.

As the reinforcing member in the vehicle width direction, the above-mentioned No. In addition to the one cross member 18, each extends in the vehicle width direction. 2 cross member 20, sub cross member 22, No. 2 3 cross member 24; 4 cross members 26 are arranged.
No. 2 Both left and right ends of the cross member 20 are joined to the side sill 12, the inner end in the vehicle width direction of the sub cross member 22 is joined to the floor side frame 14, and the outer end in the vehicle width direction is joined to the rear side frame 16. Has been. No. The left and right ends of the 3 cross member 24 are joined to the rear side frame 16, respectively. The rear end portion of the floor side frame 14 described above is joined to the 3 cross member 24. No. The left and right ends of the 4 cross member 26 are joined to the rear side frame 16.

  As described above, the floor panels 2, 4, and 6 are provided with the side sills 12, the pair of floor side frames 14, and the pair of rear side frames 16 as the reinforcing structure in the vehicle longitudinal direction. As a reinforcing structure, No. 1 cross member 18, no. 2 cross member 20, sub cross member 22, No. 2 3 cross member 24 and No. 3 4 cross members 26 are provided, which can sufficiently secure the bending rigidity and torsional rigidity of the body of the automobile, and minimize the deformation of the passenger compartment particularly at the time of a frontal collision or a side collision of the automobile. The occupant can be reliably protected.

Next, the floor panel will be specifically described with reference to FIG. The front floor panel 2 is formed by integrally pressing a steel plate, and a floor tunnel portion 40 that bulges upward at a substantially central position in the vehicle width direction extends in the longitudinal direction of the vehicle body. The floor tunnel portion 40 extends to the vehicle body rear end of the center floor panel 4.
The front floor panel 2 includes a side sill 12, a floor side frame 14, a rear side frame 16, and a floor tunnel portion 40 that extend in the vehicle longitudinal direction at both left and right ends in the vehicle width direction, and cross members 18 and 20, each extending in the vehicle width direction. It is comprised from eight floor panel parts S1-S8 surrounded by 22 and 24.

The floor panel portions S1 and S2 constitute a part of the front floor panel 2 that is integrally molded, and the side sill 12 and the floor side frame 14, which are frame members on the left and right sides of the floor tunnel portion 40, respectively. 1 cross member 18 and No. 1 2 It is provided in a space surrounded by the cross member 20, and its peripheral edge is joined to each frame member 12, 14, 18, 20.
The floor panel portions S3 and S4 constitute a part of the front floor panel 2 that is integrally molded, and the side sill 12, the floor side frame 14, and the No. 4 frame members which are frame members on the left and right sides of the floor tunnel portion 40, respectively. It is provided in a space surrounded by the two cross members 20 and the sub cross member 22, and its peripheral edge is joined to each frame member 12, 14, 20, 22.

The floor panel portions S5 and S6 constitute a part of the front floor panel 2 that is integrally molded, and the rear side frame 16, floor side frame 14, sub-cross member 22, and frame members on the left and right sides of the floor tunnel portion 40, respectively. No. It is provided in a space surrounded by the three cross members 24, and the periphery thereof is joined to each frame member 14, 16, 22, 24.
The floor panel portions S7 and S8 constitute a part of the front floor panel 2 that is integrally formed. The floor tunnel portion 40 and the floor side frame 14 that is a frame member and the No. 1 frame are respectively formed on the left and right sides of the floor tunnel portion 40. It is provided in a space surrounded by the three cross members 24, and the outer edges of the two sides are joined to the frame members 14 and 24.

  The center floor panel 4 is formed by integrally pressing a steel plate, and a floor tunnel portion 40 that bulges upward at a substantially central position in the vehicle width direction extends in the longitudinal direction of the vehicle body. The center floor panel 4 includes a floor tunnel portion 40 on each of the left and right sides of the floor tunnel portion 40, a rear side frame 16, which is a frame member, 3 cross member 24 and No. 3 It consists of floor panel portions S9 and S10 surrounded by four cross members 26. As for floor panel part S9 and S10, the outer edge of the three sides is joined to each frame member 16,24,26.

  The rear floor panel 6 is formed by integrally press-molding steel plates. 4 cross member 26, floor panel part S11 surrounded by rear body 42 which is a vehicle body structural member, and rear side frame 16 which is a frame member on both sides in the vehicle width direction, rear body 42 and wheel which are a vehicle body structural member The floor panel portions S12 and S13 are surrounded by the house 44. The peripheral edge of the floor panel portion S11 is joined to the frame members 16, 26 and the rear body 42, and the peripheral edges of the floor panel portions S12, S13 are joined to the frame member 16, the rear body 42 and the wheel house 44. .

  In such an underbody 1 of an automobile, vibration and road noise of the engine 28, the front suspension 32, and the rear suspension 36 are respectively transmitted through the front side frame 10, the front suspension cross member 30, and the rear suspension cross member 34. The vibrations and the road noise are transmitted to the floor panel portions S1 to S13, respectively, transmitted to the frame members 12, 14, 16, 18, 20, 22, 24, and 26 connected thereto.

  As described above, the vibration transmitted from the engine or suspension to the frame member is mainly in the frequency band near 250 Hz that is the cavity resonance frequency of the tire and the frequency band near 160 Hz that is the road noise due to the resonance of the suspension. Therefore, in this embodiment, the vibration mode adjustment structure is provided in the floor panel portions S1, S2, S5, and S6, so that the vibrations transmitted from the frame members 12, 14, 16, 18, 20, 22, 24, and 26 are caused. The floor panel portions S1, S2, S5, and S6 suppress the radiated sound in the frequency band near 250 Hz, and also suppress the radiated sound in the frequency band near 160 Hz, which is road noise due to suspension resonance. In addition, floor panel part S3, S4, S7 thru | or S13 are comprised by the conventional flat panel.

  Next, the floor panel structure of the vehicle body of the present embodiment will be specifically described with reference to FIGS. 2 is a conceptual diagram showing cancellation (cancellation) of radiated sound of the floor panel of the vibration mode adjustment structure, FIG. 3 is a schematic diagram showing a strut type suspension, and FIG. 4 is a diagram of this embodiment. FIG. 5 is an enlarged plan view showing the front floor panel 2, and FIG. 5 is a cross-sectional view taken along the line VV in FIG.

The vibration mode adjustment structure in the floor panel structure of the vehicle body of this embodiment is configured to vibrate the floor panel in a predetermined vibration mode having a low acoustic radiation efficiency at a predetermined frequency.
The basic principle of this vibration mode adjustment structure is described in detail in the above-mentioned Patent Document 1 (Japanese Patent Laid-Open No. 9-202269). In short, when the number of vibration antinodes excited in the vertical and horizontal directions of the rectangular vibration region is n and m, respectively, as shown in FIG. 2, if “n × m = even”, The sound radiated from the opposite-phase portions adjacent to each other in the panel cancel each other, and the sound radiation efficiency is greatly reduced.
On the other hand, in the 1 × 1 vibration mode in which one vibration antinode is generated in the vibration region, there is no portion that vibrates in reverse phase, and the acoustic radiation efficiency is large.

  As described above, the radiated sound from the floor panel is generated by engine and suspension vibrations and road noise transmitted from the frame members 12, 14, 16, 18, 20, 22, 24, and 26. In the present embodiment, vibration mode adjustment structures are provided in the floor panel portions S1, S2, S5, and S6 so as to reduce the radiated sound caused by the tire cavity resonance frequency that appears mainly in the frequency band near 250 Hz. In the present embodiment, a frequency band of 220 to 260 Hz as such a frequency band is set as a set target value for acoustic radiation reduction.

  Further, in the floor panels S1, S2, S5 and S6, radiation caused by road noise due to suspension resonance is prevented so that a 1 × 1 vibration mode does not occur in a frequency band near 160 Hz which is a problem in a vehicle having a strut suspension. The sound is reduced. In the present embodiment, a frequency band of 120 to 180 Hz as such a frequency band is set as a set target value for acoustic radiation reduction. Since the frequency band (set target value) of vibration generated by suspension resonance differs depending on the suspension type, in the case of other types of suspension such as W wishbone, the set target value is another value.

  FIG. 3 is a schematic view showing a strut type suspension. The suspension arm 54 is connected to the lower end of the knuckle spindle 52 of the front wheel 50 by a ball joint 56, and the lower end of the damper 58 is connected to the upper end of the knuckle spindle 52 by a rigid (the coupling portion is represented by a black circle). . The upper end of the damper 58 is connected to the tire house of the vehicle body.

  First, the floor panel structure of the vehicle body of the floor panel portions S1 and S2 according to the present embodiment will be described with reference to FIGS.

  As shown in FIG. 4, the floor panel portions S <b> 1 and S <b> 2 have side edges 12, floor side frames 14, and No. 4 edges. 1 cross member 18 and No. 1 It is surrounded by two cross members 20. The floor panel portion S1 has a vibration region S1a surrounded by a substantially square shape so that a 2 × 2 mode vibration mode is easily generated. Further, the floor panel portion S2 is provided with a reinforcing bead portion 60 for securing the strength of the floor panel, and a region S2a in which the reinforcing bead portion 60 is provided, that is, a broken line and frame members 14 and 18 in FIG. , 20 is less likely to cause a specific vibration mode, but the remaining region S2b, that is, the region surrounded by the broken line and the frame members 12, 18, 20 in FIG. It has a rectangular shape with a size of 2 × 1, and a 2 × 1 mode vibration mode is easily generated.

In the vibration region S1a of the floor panel portion S1, the rigidity of the floor panel portion S1 is such that 2 × 2 mode vibrations are generated in a frequency band near 250 Hz and no 1 × 1 mode vibrations are generated in a frequency band near 160 Hz. There are four substantially square stiffness adjusting portions 62 for partially adjusting the vehicle body in the vehicle longitudinal direction and the vehicle width direction so as to correspond to the shape of the vibration region S1a.
Further, in the vibration region S2b of the floor panel S2, the 2 × 1 mode vibration is generated in the frequency band near 250 Hz and the 1 × 1 mode vibration is not generated in the frequency band near 160 Hz. Two substantially square stiffness adjusting portions 62 for partially adjusting the stiffness are formed side by side along the longitudinal direction of the rectangular vibration region S2b in the longitudinal direction of the vehicle body.

  These rigidity adjusting portions 62 are formed in a substantially square shape and occupy a relatively large area in each of the vibration regions S1a and S2b, and the portions provided with the rigidity adjusting portions 62 are respectively 2 × 2 mode. And 2 × 1 mode vibration antinodes. In other words, the region where the antinodes of 2 × 2 mode and 2 × 1 mode vibration occur is defined by the stiffness adjusting unit 62. All of these rigidity adjusting portions are formed to have substantially the same size so that the vibration volumes of the antinodes of four or two vibrations are the same.

  In addition, these substantially square rigidity adjusting portions 62 are parallel to each other with one side of each of the adjacent rigidity adjusting portions facing each other, and a straight, elongated flat panel portion 64 is provided between the rigidity adjusting portions. They are arranged to form. That is, in the floor panel portion S1, the four flat panel portions 64 that extend in a straight line with a substantially constant width so that the four rigidity adjusting portions 62 intersect each other at substantially the center of the vibration region S1a to form a cross shape. In the floor panel portion S2, an elongated flat panel extending in a straight line with a substantially constant width in a direction substantially perpendicular to the longitudinal direction in the middle of the longitudinal direction of the rectangular vibration region S2b. A portion 64 is formed.

As described above, in the present embodiment, by forming the straight, elongated flat panel portion 64 by each stiffness adjusting portion 62, a vibration node is generated in the panel portion 64 between the adjacent stiffness adjusting portions 62. I am doing so.
Note that the shape of the rigidity adjusting portion is not limited to the above-described square, but may be a rectangular shape such as a rectangle, and the respective sides of the rigidity adjusting portions adjacent to each other face each other and are parallel to each other. It is sufficient to arrange so as to form a straight elongated flat panel portion 64 therebetween.

Next, as shown in FIG. 5, these rigidity adjusting portions 62 in the panel portions S <b> 1 and S <b> 2 are formed so that the cross-section thereof protrudes the floor panel portion S <b> 1 or S <b> 2 itself downward, and the curvature continuously changes. In this way, it is composed of a curved surface portion (protruding portion) 66 whose rigidity is increased and a step portion 68 formed on the outer peripheral edge portion thereof, and the rigidity of the rigidity adjusting portion 62 is enhanced by this step portion 68. . The step portion 68 includes a vertical portion (rising portion) 68a extending substantially vertically from the flat panel portion and a horizontal portion 68b extending inward from the lower edge of the vertical portion 68a, and the curved surface portion 66 includes the step portion. In the vicinity of 68, a rising portion 66a is provided.
The rigidity adjusting portion 62 is formed such that the rising portion 68a of the stepped portion 68 is closer to the vertical than the rising portion 66a of the protruding portion 66, and the vertical portion 68a of the stepped portion 68 is bent at an acute angle from the flat panel portion. That is, the normal direction of each of the flat panel portion and the vertical portion 68a is discontinuous.

Here, as described above, the height of the rigidity adjusting unit 62 needs to be adjusted within a predetermined range due to restrictions on the vehicle body structure or processing, and when there is such a limitation, the stepped portion 68 is provided. If the rigidity adjusting portion is constituted only by the curved surface portion (projecting portion) 66, the angle at which the curved surface portion (projecting portion) extends inward from the flat panel portion, that is, the rising portion of the curved surface portion (projecting portion) is flat. The angle with respect to the panel portion cannot be increased, and the rigidity cannot be increased to a desired size.
Therefore, in the present embodiment, the stepped portion 68 is provided, and the rising portion 68a of the stepped portion 68 is formed at an angle closer to the vertical than the rising portion 66a of the protruding portion 66 so as to increase rigidity and press forming accuracy. ing. Such an angle of the vertical portion (rising portion) may be an angle that can obtain a desired rigidity and can increase the press forming accuracy of the rigidity adjusting portion, and is appropriate depending on the thickness of the floor panel. The angle is determined.

  The rigidity adjusting portion 62 may protrude upward. In this case as well, as described above, the rising portion 68a of the stepped portion 68 is formed at an angle closer to the vertical than the rising portion 66a of the protruding portion 66. Good. Further, the curved surface portion (projecting portion) 66 does not have to be such that the curvature continuously changes, and may be partially bent or formed with a bead or the like.

  The rigidity of the rigidity adjusting portion 62 is adjusted by adjusting the curvature and height of the curved surface portion 66, the height of the vertical portion 68a of the stepped portion 68, and the width of the horizontal portion 68b. The rigidity of the floor panel parts S1 and S2 is partially adjusted by adjusting the rigidity of the floor panel parts S1 and S2, and the vibration modes of 2 × 2 and 2 × 1 are respectively applied to the floor panel parts S1 and S2 in a frequency band near 250 Hz. In addition, the 1 × 1 vibration mode is prevented from being generated in a frequency band near 160 Hz.

  Further, in the present embodiment, the vertical portion 68a of the stepped portion 68 of the rigidity adjusting portion 62 rises substantially vertically from the flat floor panel surface to increase the press forming accuracy of the rigidity adjusting portion 62, and the rigidity adjusting portion 62. Variations in the rigidity of the steel are reduced.

Next, referring to FIG. 6, first to third modifications of the rigidity adjusting unit 62 described above will be described. FIG. 6 is a cross-sectional view showing a rectangular stiffness adjuster according to first to third modifications of the present embodiment.
In the first modification shown in FIG. 6A, the stepped portion 68 as described above is formed in an arc shape. Even in this case, the rising portion 68 a of the stepped portion 68 may be formed at an angle closer to the vertical than the rising portion 66 a of the protruding portion 66.
In the second modification shown in FIG. 6B, a bead portion 69 is provided instead of the stepped portion 68 as described above. The bead portion 69 is disposed adjacent to the curved surface portion 66 so as to function in the same manner as the stepped portion 68 and extends around the bead portion 69, and the bead portion 69 and the curved surface portion 66 constitute a rigidity adjusting portion. I am doing so.

  Further, as in the third modified example shown in FIG. 6C, the rigidity adjusting portion 62 may not be provided with a step portion. In this case, it is not necessary to press the stepped portion, and the processing cost can be reduced. In addition, since it is relatively easy to form the rigidity adjusting portion so that the rigidity is lower than that of the rectangular rigidity adjusting portion provided with the stepped portion, for example, the vibration of 1 × 1 mode is a frequency band around 160 Hz. When it is not desired to increase the rigidity much, such as when it is generated at a lower frequency, it becomes easier to adjust the dimensions of the rigidity adjusting portion so that the 1 × 1 vibration mode is not generated in the frequency band near 160 Hz.

Next, the effect of the vibration mode adjustment structure provided in the floor panel portions S1 and S2 according to the present embodiment will be described.
In the panel portions S1 and S2 of the floor panel structure of the present embodiment, the floor panel portions S1 and S2 have a low acoustic radiation efficiency of 2 × 1 or 2 × in a frequency band near 250 Hz, which is road noise due to tire cavity resonance. 2 vibration modes can be generated and the vibration amplitude itself can be reduced to reduce the sound emitted from the vibration region. Furthermore, the 1 × 1 vibration mode with high acoustic radiation efficiency does not occur in the frequency band near 160 Hz, which is road noise due to the resonance of the suspension, and the radiated sound in that frequency band can also be reduced. This will be specifically described below.

First, the effect of reducing radiated sound generated by road noise due to tire cavity resonance by the vibration mode adjusting structure of the present invention will be described.
In the panel portions S1 and S2 of the floor panel structure of the present embodiment, the rectangular rigidity adjusting portion 62 is formed side by side corresponding to the shape of the vibration regions S1a and S2b, so that it substantially matches the cavity resonance frequency of the tire. Since 2 × 2 mode or 2 × 1 mode vibration is generated in the frequency band near 250 Hz and the vibration volume of the antinodes of the four or two vibrations is made the same, radiation from these vibration regions Sound can be reduced.

  In particular, since the rigidity adjusting portion 62 is formed in a rectangular shape, it is possible to easily define a region where vibration antinodes occur, and as a result, the vibration volumes of adjacent vibration antinodes are the same. Therefore, the effect of canceling out the radiated sound due to the antinodes of the even number of vibrations that vibrate in the opposite phase can be more reliably exhibited, and the acoustic radiation efficiency can be greatly reduced.

  Further, since the rigidity adjusting portion 62 is formed in a rectangular shape, the vibration amplitude itself of the vibration of the 2 × 2 mode or the 2 × 1 mode generated in the frequency band near 250 Hz can be reduced. Radiated sound from the vibration areas S1a and S2b can be further reduced.

  Further, since the rigidity adjusting portion 62 is formed in a rectangular shape and a straight and slender flat panel portion 64 is formed between the adjacent rigidity adjusting portions 62, a vibration node is surely provided on the panel portion 64. The position where the vibration node is generated can be defined, and as a result, the vibration volume of the antinode of the four or two vibrations can surely generate the vibration of 2 × 2 mode or 2 × 1 mode. I can do it.

  Next, the effect of reducing radiated sound generated by road noise due to suspension resonance by the vibration mode adjusting structure of the present invention will be described.

In the panel portions S1 and S2 of the floor panel structure of the present embodiment, the rigidity adjusting portion 62 is formed in a rectangular shape, so that vibration of 1 × 1 mode is generated rather than forming the rigidity adjusting portion in a circular shape. It can be made difficult.
Here, when a 1 × 1 vibration mode with one vibration anti-node occurs, the anti-vibration of the vibration so as to rise to a large curved surface within the vibration region of the floor panel, that is, its cross section is For example, a distribution is made by drawing a sine curve and deforming it.
By the way, the rigidity adjustment amount of the floor panel by the two or four rigidity adjusting portions necessary for generating the 2 × 1 or 2 × 2 vibration mode in a frequency band near 250 Hz substantially matching the cavity resonance frequency of the tire is Even if the rigidity adjusting portion is formed in a circular shape or a rectangular shape, it is the same level.

  However, when vibration of a frequency at which 1 × 1 mode vibration is generated is transmitted from the frame member, when the rigidity adjustment portion is formed in a circular shape, the vibration of 1 × 1 mode is reduced to the circular rigidity adjustment portion. In the region where the two stiffness adjusting portions near the center of the antinode of vibration having a large amplitude face each other, the outer peripheral edge portion is formed in an arc shape. Therefore, it does not significantly suppress the occurrence of 1 × 1 mode vibration against the antinode of vibrations that rise to a curved surface.

  On the other hand, when the rigidity adjusting portion is formed in a rectangular shape, a region where 1 × 1 mode vibration antinodes are generated even when vibration of a frequency at which 1 × 1 mode vibration is generated is transmitted from the frame member. Since the outer peripheral edge of the rigidity adjusting portion is formed in a straight line, it is difficult to cause deformation due to such vibration that tends to rise to a curved surface, and vibration with a large amplitude is generated. Even in the region where the two stiffness adjusting portions near the center of the belly face each other, the linear outer peripheral edge portions of the two stiffness adjusting portions face each other, thereby causing a curved deformation due to vibration of 1 × 1 mode. As a result, it is possible to suppress the occurrence of 1 × 1 mode vibration.

In addition, even when 1 × 1 mode vibration occurs, the rectangular rigidity adjusting unit 62 having a linear outer peripheral edge has a higher frequency than the case where the rigidity adjusting unit 62 is formed in a circular shape. Thus, in the frequency band in which the 2 × 1 or 2 × 2 vibration mode is generated, that is, in the floor panel portions S1 and S2 of the present embodiment, the frequency band can be close to 250 Hz.
As a result, the size and depth of the circular rigidity adjusting portion are adjusted within a predetermined range due to restrictions on the vehicle body structure or processing, so that the vibration in the 1 × 1 mode is not in a frequency band near 160 Hz. Even when it cannot be generated at a frequency, by forming a rectangular rigidity adjusting portion, 1 × 1 mode vibration is prevented from being generated in a frequency band near 160 Hz, so that road noise caused by resonance of the suspension Radiation sound in a certain frequency band near 160 Hz can be reduced.

  In addition, since the rigidity adjusting portion 62 is arranged so as to form a straight, elongated flat panel portion 64 between each of the adjacent rigidity adjusting portions 62, it is difficult to generate 1 × 1 mode vibration itself. Alternatively, even if it occurs, the vibration amplitude can be reduced. In particular, in the floor panel portion S1, four rectangular rigidity adjusting portions 62 are arranged so as to form a cross-shaped elongated flat panel portion 64, and this arrangement can generate a 1 × 1 vibration mode. It can be effectively suppressed.

  Next, in the panel portions S1 and S2 of the floor panel structure of the present embodiment, the stepped portion 68 is provided on the outer peripheral edge portion of the curved surface portion 66 of the rigidity adjusting portion 62, so that the rigidity adjusting portion 62 is the only curved surface portion 66. The rigidity can be easily increased as compared with the case of the above. Further, since the rising portion 68a of the stepped portion 68 is formed at an angle closer to the vertical than the rising portion 66a of the protruding portion 66, the rigidity of the rigidity adjusting portion 62 can be increased without increasing the height of the rigidity adjusting portion 62. Can be increased.

  Further, by providing the stepped portion 68 at the outer peripheral edge of the curved surface portion 66, the frequency at which the 1 × 1 vibration mode is generated can be set to 1 × 1 mode more than the rectangular rigidity adjusting portion without the stepped portion. The vibration itself can be made less likely to occur, or even if it occurs, the generated frequency can be made closer to the frequency at which the 2 × 1 or 2 × 2 vibration mode is generated. As a result, it is possible to prevent the 1 × 1 vibration mode from occurring in a frequency band near 160 Hz.

  Further, since the stepped portion 68 has a vertical portion 68a that is formed at an angle closer to the vertical than the rising portion of the protruding portion and rises substantially vertically from the floor panel, the molding accuracy of the rigidity adjusting portion 62 is increased during press molding. As a result, the processing variation of the rigidity of the rigidity adjusting unit 62 is reduced, and the 2 × 2 and 2 × 1 vibration modes are reliably generated in the floor panel portions S1 and S2 in the frequency band near 250 Hz. I can do it.

Next, the floor panel structure of the vehicle body of the floor panel portions S5 and S6 of the present embodiment will be described with reference to FIGS. 7 is a cross-sectional view taken along line VII-VII in FIG.
As shown in FIGS. 4 and 7, the floor panel portion S <b> 5 has four side edges, the floor side frame 14, the rear side frame 16, the sub-cross member 22, and No. 4 respectively. Surrounded by three cross members 24. The floor panel portion S5 is provided with a reinforcing bead portion 46 for securing the strength of the floor panel.

In the floor panel S5 of the present embodiment, as shown in FIG. 4, acoustic vibration is radiated in a frequency band near 250 Hz, which is road noise due to tire cavity resonance, in the vibration region S5a of the floor panel portion S5 as a vibration mode adjustment structure. An approximately circular shape is generated so that a low-efficiency 2 × 1 or 2 × 2 vibration mode is generated and a high-acoustic radiation efficiency 1 × 1 vibration mode is not generated in a frequency band near 160 Hz, which is road noise due to suspension resonance. The two stiffness adjusting portions 72 are formed side by side in the longitudinal direction of the vehicle body so as to correspond to the shape of the vibration region S5a.
As shown in FIGS. 4 and 6, these rigidity adjusting portions 72 are formed so that the outer periphery thereof is substantially circular and the floor panel S <b> 5 itself protrudes downward in a dome shape.

  In the floor panel section S5 of the present embodiment, in the vibration region S5a, a 2 × 1 or 2 × 2 vibration mode is generated in a frequency band near 250 Hz, and a 1 × 1 vibration mode is not generated in a frequency band near 160 Hz. As described above, the diameter, the curvature and the height of the substantially circular rigidity adjusting portion 72 are adjusted and the arrangement thereof is adjusted. In addition, by such adjustment, the vibration volumes of the two antinodes of the 2 × 1 mode are made the same.

  Also in the floor panel portion S6, as in the floor panel portion S5, the floor side frame 14, the rear side frame 16, the sub cross member 22, No. 4 Two substantially circular rigidity adjusting portions 72 are provided in the vibration region S6a, which is a region surrounded by the three cross members 24 and the reinforcing bead portions 46.

Next, the effect of the vibration mode adjustment structure provided in the floor panel portions S5 and S6 according to the present embodiment will be described.
The vibration regions S5a and S6a of the floor panel portions S5 and S6 are provided with a substantially circular stiffness adjusting portion 72, which is a vibration mode adjusting structure, respectively, so that 2 in a frequency band near 250 Hz substantially matching the cavity resonance frequency of the tire. Since the vibration of the × 1 mode is generated and the vibration volume of the antinodes of the two vibrations is made the same, the radiated sound from this vibration region can be reduced.

In addition, in these vibration regions S5a and S6a, the shape of the rigidity adjusting portion is not a rectangular shape but a circular shape according to the specific conditions such as the size, shape, and plate thickness of the vibration regions S5a and S6a. Therefore, it is possible to prevent a 1 × 1 vibration mode with high acoustic radiation efficiency from occurring in a frequency band near 160 Hz, which is road noise due to suspension resonance.
That is, the circular rigidity adjusting unit can prevent the frequency at which the 1 × 1 vibration mode is generated from being increased so much as the rectangular rigidity adjusting unit due to the difference in shape and rigidity. If a 1 × 1 vibration mode is generated in a frequency band lower than the frequency band near 160 Hz on a flat floor panel, select a circular rigidity adjustment section instead of a rectangular rigidity adjustment section. The frequency at which the 1 × 1 vibration mode is generated is not so high, and the 1 × 1 vibration mode with high acoustic radiation efficiency is not generated in the frequency band near 160 Hz.

Therefore, in addition to the frequency band near 250 Hz that is road noise due to tire cavity resonance, acoustic radiation in the frequency band near 160 Hz that is road noise due to suspension resonance can also be reduced.
In addition, the circular rigidity adjusting portion is less likely to cause bending vibration or torsional vibration in the rigidity adjusting portion itself, and can effectively reduce radiated sound.
In addition, the circular stiffness adjuster has better processability than the rectangular stiffness adjuster and can be easily pressed when the stiffness adjuster is formed on the floor panel, thus reducing processing costs. I can do it.

Next, with reference to FIGS. 8 and 9, a modified example of the rectangular rigidity adjusting portion which is the vibration mode adjusting structure of the above-described embodiment will be described as an example applied to the region of the floor panel portion S5 described above.
FIGS. 8A, 8B, 9A, and 9B are respectively a first modification, a second modification, a third modification, and a fourth modification of the vibration mode adjustment structure. It is a top view which shows an example.

  In these first to fourth modifications, the floor side frame 14, the rear side frame 16, the sub cross member 22, and the No. 4 are not provided in the floor panel portion S 5 without providing the reinforcing bead portion 46. A rigidity adjustment portion 62 that is a vibration mode adjustment structure is provided in a non-rectangular vibration region S5a 'that is a region surrounded by the three cross members 24. The rigidity adjusting portion 62 is the same as the rigidity adjusting portion provided on the floor panel portions S1 and S2 shown in FIG. 5 described above, and is formed on a curved surface portion 66 formed so as to protrude downward and on an outer peripheral edge portion thereof. And a stepped portion 68.

  Specifically, as shown in FIG. 8 (a), the vibration mode adjustment structure according to the first modification is formed by forming two substantially square rigidity adjustment portions 62, and a non-rectangular vibration region S5a. It is shifted in the vehicle width direction corresponding to '. In addition, one side of each of the rigidity adjusting portions 62 is opposed and parallel to each other, and a straight, elongated flat panel portion 64 is formed between adjacent rigidity adjusting portions 62.

  As shown in FIG. 8 (b), the vibration mode adjustment structure according to the second modification is formed by forming two substantially square stiffness adjusting portions 62, and each side of each stiffness adjusting portion 62 has two sides. They are arranged so as to extend in a direction substantially perpendicular to or parallel to the straight line f passing through the middle of the long sides d and d ′. In the present modification, the centroids of the two substantially square rigidity adjusting portions 62 are arranged on the straight line f. By arranging the two rigidity adjusting portions 62 in this way, the respective sides of each of the rigidity adjusting portions 62 are opposed and parallel to each other, and are linearly elongated between the adjacent rigidity adjusting portions 62. A flat panel portion 64 is formed.

  As shown in FIG. 9A, the vibration mode adjustment structure according to the third modification is formed with two rectangular rigidity adjustment portions 62 having different sizes, and has a rigidity on the side close to the short side e. The adjustment portion 62 is formed in a substantially rectangular shape, and the rigidity adjustment portion 62 on the side close to the short side e ′ is formed in a substantially square shape. In addition, one side of each of the rigidity adjusting portions 62 is opposed and parallel to each other, and a straight, elongated flat panel portion 64 is formed between adjacent rigidity adjusting portions 62.

  As shown in FIG. 9B, the vibration mode adjustment structure according to the fourth modification is formed with two rectangular rigidity adjustment portions 62 having different sizes and shapes, and is closer to the short side e. The rigidity adjusting portion 62 is formed in a substantially rectangular shape, and the rigidity adjusting portion 62 on the side near the short side e ′ is formed in a substantially square shape. The rigidity adjusting portions 62 have sides adjacent to the frame members 14, 16, 22, 24 along the short sides e, e ′ or the long sides d or d ′ of the frame members 14, 16, 22, 24, respectively. It is formed to extend. In addition, one side of each of the rigidity adjusting portions 62 is opposed and parallel to each other, and a straight, elongated flat panel portion 64 is formed between adjacent rigidity adjusting portions 62. In the modification shown in FIG. 9 (b), the rigidity adjustment unit 62 occupies a large area in the vibration region S5a ′, and each rigidity adjustment unit 62 ensures that the two antinodes of the 2 × 1 mode have vibration. Each is an area where it occurs. In addition, you may make it each adjacent edge | side of each rigidity adjustment part 62 extend in the direction substantially orthogonal to the straight line f which passes through the substantially middle of two long sides d and d '.

  Also in these first to fourth modified examples, by providing the rigidity adjusting unit 62, the non-rectangular vibration region S5a ′ is 2 × 1 in a frequency band near 250 Hz that substantially matches the cavity resonance frequency of the tire. Mode vibration is generated, and 1 × 1 mode vibration is not generated in a frequency band near 160 Hz, which is road noise due to suspension resonance.

  Further, in both the first and second modified examples, the two rigidity adjusting portions 62 are arranged so as to approach the front side in the longitudinal direction of the vehicle body, that is, the longer short side e of the short sides e and e ′. Then, the vibration volume of the antinodes of the two vibrations in the 2 × 1 mode is adjusted to be the same. In the third and fourth modified examples, the size and position of the two stiffness adjusting parts 62 are adjusted so that the vibration volumes of the two antinodes of the 2 × 1 mode are the same. Yes.

  In these modified examples, in order to make the vibration volumes of the two vibrations the same, the two rigidity adjusting parts 62 are each made to have a rectangular size, a curvature and a height of the curved surface part 66, and a step part. 68 may be formed to have different heights and widths.

Next, an embodiment of a method for manufacturing a floor panel having a vibration mode adjustment structure according to the present invention will be described with reference to FIG. FIG. 10 is a flow showing a manufacturing method using the design method of the floor panel having the vibration mode adjustment structure according to the present embodiment.
In this manufacturing method, the acoustic radiation from the floor panel is selected from a circular rigidity adjustment part as a vibration mode adjustment structure, a rectangular rigidity adjustment part without a step part, or a rectangular rigidity adjustment part with a step part. In order to reduce this, a design method is adopted in which an appropriately shaped rigidity adjusting portion is selected and formed on the floor panel.

First, the manufacturing method according to the present embodiment will be specifically described with reference to FIG. In FIG. 10, S indicates each step.
In the present embodiment, among the steps described below, in each step except S3, S7, and S9, setting of the stiffness adjusting unit to the floor panel is performed by analysis using CAE (for example, FEM (finite element method)). Alternatively, the dimensions are adjusted to estimate the vibration mode and vibration frequency generated in the floor panel, and are used as a reference for determining the shape of the rigidity adjusting portion. In such an analysis, taking advantage of the advantage, as a condition specific to the vehicle body where the floor panel is provided, the difference in the cavity resonance frequency of the tire depending on the type of tire to be installed, the frequency band where radiated sound is a problem, etc. The acoustic radiation level is considered in detail.

  First, in S1, the floor panel is provided with a predetermined circular rigidity adjusting portion that protrudes upward or downward so that 2 × 1 mode or 2 × 2 mode vibration is generated in a frequency band near 250 Hz. Set. In the present embodiment, the frequency band of 220 to 260 Hz is set as the target value of the 2 × 1 mode or 2 × 2 mode generation frequency as the frequency band near 250 Hz.

In S1, for example, as described in the floor panel portions S4 and S5 described above, the circular rigidity adjusting portion 72 is set in the vibration region of the floor panel.
In S <b> 1, a predetermined standard size stiffness adjusting unit is set as a predetermined circular stiffness adjusting unit. This standard dimension is based on data such as a stiffness adjustment unit provided in an experiment or another vehicle.
Further, as a predetermined stiffness adjusting portion, 2 × 1 mode (or 2 × 2 mode) is generated from the frequency of vibration of 2 × 1 mode or 2 × 2 mode generated on a flat floor panel before the rigidity adjusting portion is provided. It is also possible to predict the amount of rigidity necessary to generate the frequency in the frequency band near 250 Hz and determine the dimension from the amount of rigidity.

  Here, the vibration region of the floor panel portion refers to a certain region surrounded by a frame member, a reinforcing bead portion or the like in the floor panel. For example, in the floor panel of the above-described embodiment shown in FIG. In the region S1a surrounded by the frame members 12, 14, 18 and 20 in the panel portion S1, the vibration region S2b surrounded by the broken line and the frame members 14, 18, and 20 in the floor panel portion S2, and the floor panel portion S5 This is a region such as a region S <b> 5 a surrounded by the frame members 14, 16, 22, and 24 and the reinforcing bead portion 46.

  Next, the process proceeds to S2, and it is determined whether or not the 1 × 1 mode vibration is generated in the frequency band near 160 Hz on the floor panel provided with the circular rigidity adjusting unit set in S1. In this embodiment, the frequency band of 120 to 180 Hz is set as the target value as the frequency band near 160 Hz.

  If it is determined in S2 that 1 × 1 mode vibration does not occur in the frequency band near 160 Hz, the process proceeds to S3, and the rigidity adjustment unit having the same size and arrangement as the circular rigidity adjustment unit set in S1 is set to the floor panel. To form.

  When it is determined in S2 that the vibration in the 1 × 1 mode occurs in the frequency band near 160 Hz, the process proceeds to S4, and the dimensions of the circular rigidity adjusting portion are adjusted within a predetermined range, so that the 2 × 1 mode or It is determined whether the 2 × 2 mode vibration can be generated in a frequency band near 250 Hz and the 1 × 1 mode vibration can be generated in a frequency other than the frequency band near 160 Hz.

  Here, as a predetermined range for adjusting the dimension of the circular rigidity adjusting portion, for example, when the rigidity adjusting portion is formed to protrude downward, the vehicle body below the floor panel on which the rigidity adjusting portion is to be formed. If the exhaust pipe passes through, the range of the height of the rigidity adjustment part so that it does not interfere with the exhaust pipe. If the floor panel is too thick and difficult to press, the press workable range (yen And the range of the outer diameter of the rigidity adjusting portion that fits in the vibration region of the floor panel on which the rigidity adjusting portion is to be formed.

  The determination in S4 is performed by analyzing a plurality of rigidity adjusted portions adjusted in size by CAE as described above, and determining from the result, or determining from a database such as experimental data.

  In S4, the dimensions of the circular rigidity adjusting portion are adjusted within a predetermined range to generate 2 × 1 mode or 2 × 2 mode vibrations in a frequency band near 250 Hz and 1 × 1 mode vibrations near 160 Hz. When it is determined that the frequency can be generated at a frequency other than the frequency band, the process proceeds to S3 to generate a vibration of 2 × 1 mode or 2 × 2 mode in a frequency band near 250 Hz and a vibration of 1 × 1 mode. A circular rigidity adjusting portion adjusted to a size that can be generated at a frequency other than the frequency band near 160 Hz is formed on the floor panel.

  In S4, the dimensions of the circular rigidity adjusting portion are adjusted within a predetermined range to generate 2 × 1 mode or 2 × 2 mode vibrations in a frequency band near 250 Hz and 1 × 1 mode vibrations near 160 Hz. When it is determined that it cannot be generated at a frequency other than the above frequency band, the process proceeds to S5, and the floor panel itself is moved upward so as to generate 2 × 1 mode or 2 × 2 mode vibration in a frequency band near 250 Hz. Or the rectangular-shaped rigidity adjustment part protruded below is set to a floor panel. Note that the stepped portion 68 (see FIG. 5) described above is not provided in the rectangular rigidity adjusting portion set in S5.

  Here, as described in the floor panel portions S5 and S6 according to the above-described embodiment, when the rigidity adjusting portion is formed in a rectangular shape, the 1 × 1 mode is more effective than when the rigidity adjusting portion is formed in a circular shape. It is difficult to generate the vibration itself, or even if it occurs, the generated frequency can be made closer to the frequency at which the 2 × 1 or 2 × 2 vibration mode is generated. Therefore, in step S5 and subsequent steps, the shape of the stiffness adjuster is changed from a circular shape to a rectangular shape to generate 2 × 1 mode or 2 × 2 mode vibrations in a frequency band near 250 Hz and 1 × 1 mode. Is generated at a frequency other than the frequency band near 160 Hz.

  Next, proceeding to S6, it is determined whether or not 1 × 1 mode vibration is generated in a frequency band near 160 Hz on the floor panel provided with the rectangular rigidity adjusting portion that is not provided with the step portion set in S5. judge.

  In S6, when it is determined that the 1 × 1 mode vibration does not occur in the frequency band near 160 Hz, the process proceeds to S7, and has the same size and arrangement as the rectangular rigidity adjusting unit provided with the stepped portion set in S5. A rigidity adjusting portion is formed on the floor panel.

  In S6, when it is determined that the vibration of the 1 × 1 mode occurs in the frequency band near 160 Hz, the process proceeds to S8, and by adjusting the dimensions of the rectangular stiffness adjuster within a predetermined range (similar to S4), It is determined whether 2 × 1 mode or 2 × 2 mode vibration can be generated in a frequency band near 250 Hz and 1 × 1 mode vibration can be generated in a frequency other than the frequency band near 160 Hz.

  In S8, the size of the rectangular rigidity adjusting portion is adjusted within a predetermined range to generate 2 × 1 mode or 2 × 2 mode vibration in a frequency band near 250 Hz, and 1 × 1 mode vibration is near 160 Hz. When it is determined that the frequency can be generated at a frequency other than the frequency band, the process proceeds to S7, and the vibration of 2 × 1 mode or 2 × 2 mode is generated in the frequency band near 250 Hz and the vibration of 1 × 1 mode is generated. A rectangular rigidity adjustment portion adjusted to a size that can be generated at a frequency other than the frequency band near 160 Hz is formed on the floor panel.

  In S8, the size of the circular rigidity adjusting portion is adjusted within a predetermined range to generate 2 × 1 mode or 2 × 2 mode vibration in a frequency band near 250 Hz and 1 × 1 mode vibration near 160 Hz. When it is determined that it cannot be generated at a frequency other than the frequency band, the process proceeds to S9, and among the rectangular stiffness adjusters whose dimensions are adjusted at S8, the value with the highest 1 × 1 mode generation frequency is obtained. A step portion is provided on the outer peripheral edge of the rectangular rigidity adjusting portion having the obtained dimensions, and the rectangular rigidity adjusting portion is formed on the actual floor panel in the arrangement set in S5.

  In S8, for example, as shown in FIG. 5, a rectangular rigidity adjusting portion 62 having a cross section composed of a curved surface portion 66 and a stepped portion 68, as shown in floor panel portions S1 and S2 shown in FIG. In step S8, the height and width of the step portion are adjusted to generate 2 × 1 mode or 2 × 2 mode vibration in a frequency band near 250 Hz and 1 × 1. The vibration mode is generated in a frequency band higher than the frequency band near 160 Hz, which is road noise caused by suspension resonance.

  Here, as described in the floor panel portions S1 and S2 according to the above-described embodiment, when the step portion is provided on the outer peripheral edge portion of the rectangular rigidity adjustment portion, the rigidity adjustment portion is not provided with the step portion. The 1 × 1 mode vibration itself can be made more difficult to generate, or the generated frequency can be made closer to the frequency at which the 2 × 1 or 2 × 2 vibration mode is generated. Therefore, in S9, the rectangular rigidity adjusting portion having the stepped portion on the outer peripheral edge generates the vibration of 2 × 1 mode or 2 × 2 mode in the frequency band near 250 Hz and the 1 × 1 mode. Vibration is generated at a frequency other than the frequency band near 160 Hz.

  In S5, a rigidity adjusting unit provided with a stepped portion is set, and in S8, the height and width of the stepped portion of the rigidity adjusting unit are readjusted so that the determination as in S8 described above is performed. Also good.

It is a top view which shows the underbody of the motor vehicle provided with the floor panel structure of the vehicle body by embodiment of this invention. It is a conceptual diagram which shows cancellation (cancellation) of the radiated sound of the floor panel of a vibration mode adjustment structure. It is a schematic diagram showing a strut type suspension. It is an enlarged plan view showing a front floor panel 2 having a vehicle body floor panel structure according to an embodiment of the present invention. It is sectional drawing seen along the VV line of FIG. It is sectional drawing which shows the rectangular-shaped rigidity adjustment part by the 1st thru | or 3rd modification of this embodiment. It is sectional drawing seen along the VII-VII line of FIG. It is a top view which shows the example which applied the 1st and 2nd modification of the vibration mode adjustment structure provided in floor panel part S1 and S2 of embodiment of this invention to floor panel part S5. It is a top view which shows the example which applied the 3rd and 4th modification of the vibration mode adjustment structure provided in floor panel part S1 and S2 of embodiment of this invention to floor panel part S5. It is a flow which shows the manufacturing method using the design method of the floor panel which has a vibration mode adjustment structure by this embodiment.

Explanation of symbols

2 Front floor panel 4 Center floor panel 6 Rear floor panel 10 Front side frame 12 Side sill 14 Floor side frame 16 Rear side frame 18 1 cross member 20 2 Cross member 22 Sub cross member 24 3 cross member 26 4 cross member 40 floor tunnel part 42 rear body 44 wheel house 46, 60 reinforcing bead part 62 rectangular rigidity adjusting part 64 straight and long flat panel part 66 curved part (protruding part)
66a Rising portion of protruding portion 68 Stepped portion 68a Rising portion of stepped portion 72 Circular rigidity adjusting portion S1 to S13 Floor panel portion S1a, S2a, S5a, S6a Vibration region

Claims (8)

The floor panel structure of a vehicle body has a vibration mode adjustment structure that forms a floor of an automobile by a floor panel connected to a frame member of the vehicle body and suppresses generation of acoustic radiation of the floor panel by generating vibration in a predetermined mode. And
The vibration mode adjustment structure of the floor panel moves the floor panel upward or downward so that vibration of 2 × 1 mode or 2 × 2 mode is generated in the floor panel in a frequency band that substantially matches the cavity resonance frequency of the tire. A floor panel structure for a vehicle body, comprising: a rigidity adjusting portion formed in a rectangular shape projecting into a rectangular shape. The floor panel structure of a vehicle body has a vibration mode adjustment structure that forms a floor of an automobile by a floor panel connected to a frame member of the vehicle body and suppresses generation of acoustic radiation of the floor panel by generating vibration in a predetermined mode. And
The vibration mode adjustment structure of the floor panel has a rectangular shape in which the floor panel protrudes upward or downward so that vibration of 2 × 1 mode or 2 × 2 mode is generated in the floor panel in a frequency band near 250 Hz. A floor panel structure for a vehicle body having a rigidity adjusting portion formed on the body. The floor panel structure of a vehicle body has a vibration mode adjustment structure that forms a floor of an automobile by a floor panel connected to a frame member of the vehicle body and suppresses generation of acoustic radiation of the floor panel by generating vibration in a predetermined mode. And
The vibration mode adjustment structure of the floor panel is a rigidity adjustment in which the floor panel is protruded upward or downward so that 2 × 1 mode or 2 × 2 mode vibration is generated in the floor panel in a frequency band near 250 Hz. Part
When the 1 × 1 vibration mode can be generated in a frequency band other than near 160 Hz, the rigidity adjusting portion is formed in a circular shape, and the 1 × 1 vibration mode is generated in a frequency band other than near 160 Hz. If this is impossible, the vehicle body floor panel structure is characterized in that the rigidity adjusting portion is formed in a rectangular shape.   The vibration mode adjustment structure has two rectangular rigidity adjusting portions, each side of each of the rigidity adjusting portions is opposed and parallel to each other, and an elongated panel portion is formed between the rigidity adjusting portions. The floor panel structure for a vehicle body according to any one of claims 1 to 3, wherein the floor panel structure is arranged in a position and generates a 2x1 vibration mode.   The vibration mode adjusting structure has four rectangular rigidity adjusting portions, and one side of each of the adjacent rigidity adjusting portions is parallel to each other and extends in a cross shape by the four rigidity adjusting portions. The floor panel structure for a vehicle body according to any one of claims 1 to 3, wherein the floor panel structure is arranged so as to form a portion and generates vibration of 2x2 mode.   The rectangular rigidity adjusting portion of the vibration mode adjusting structure has a step portion provided at an outer peripheral edge portion thereof, and a protrusion portion provided inward of the step portion, and the step portion and the protrusion portion. 6. The vehicle floor panel structure according to claim 1, further comprising a rising portion, wherein the rising portion of the stepped portion is formed at an angle closer to the vertical than the rising portion of the protruding portion. It has a vibration mode adjustment structure that is connected to the frame member of the vehicle body and constitutes the floor of the automobile and suppresses the generation of acoustic radiation by generating vibrations of a predetermined mode, and this vibration mode adjustment structure is circular and / or rectangular. A method for manufacturing a floor panel of a vehicle body having a shape rigidity adjusting portion,
By adjusting the dimensions of the rigidity adjusting unit within a predetermined range, vibration of 2 × 1 mode or 2 × 2 mode is generated in a frequency band near 250 Hz, and vibration of 1 × 1 mode is a frequency band other than near 160 Hz. A step of forming a circular rigidity adjusting portion,
If the 1 × 1 mode vibration cannot be generated in a frequency band other than around 160 Hz even if the dimensions of the circular rigidity adjustment part are adjusted within a predetermined range, a rectangular rigidity adjustment part is formed. And steps to
The manufacturing method of the floor panel of the vehicle body characterized by having.   In the step of forming the rectangular rigidity adjusting portion, the size of the rigidity adjusting portion is adjusted within a predetermined range so that the vibration of the 1 × 1 mode does not occur or the vibration of the 1 × 1 mode is other than around 160 Hz. If it can be generated in a frequency band, a first step of forming a rectangular rigidity adjusting portion having no stepped portion on the outer peripheral edge thereof, and a dimension of the rectangular rigidity adjusting portion within a predetermined range If the 1 × 1 mode vibration does not occur or the 1 × 1 mode vibration cannot be generated in a frequency band other than around 160 Hz even if the adjustment is performed in step 1, a rectangular shape having a stepped portion on the outer peripheral edge thereof. A method for producing a floor panel for a vehicle body according to claim 7, further comprising: a second step of forming a rigidity adjusting portion.

Images